Effective usage of the energy is realized with the use of an electricity storage device such as a secondary battery. For example, recently, solar light power generation systems are actively being developed as eco-friendly, clean energy. Because a photoelectric conversion module which converts the solar light into electric power does not have an electricity storage function, the photoelectric conversion module is in some cases used in combination with a secondary battery. For example, the energy is effectively used by charge and discharge control to charge the electric power generated by the photoelectric conversion module into the secondary battery and to discharge the electricity from the secondary battery in response to a request from an external load or the like.
As the secondary battery, for example, a lithium ion secondary battery may be used. Because the secondary battery is used for a long period of time under various environments or the like, various safety measures are desirably provided. Although various safety measures are provided in, for example, the single structure of the lithium ion secondary battery or the like, it is preferable to further improve the safety when the secondary battery is used in a state where the secondary battery is stored in a rack or the like.
For example, Patent Literature 1 discloses, as a power supply device, a power supply device which stores a plurality of batteries having a safety valve in a casing, and which has a structure in which the casing is divided by a compartment wall into a battery chamber where the plurality of batteries are stored and an exhaust chamber where the gas discharged from the safety valve of the batteries stored in the battery chamber is exhausted. In this reference, a fire extinguisher which injects extinguishing agent or inert fluid to the exhaust chamber and a pressure sensor which detects an internal pressure of the exhaust chamber are provided, the fire extinguisher is controlled by the pressure sensor, and when the internal pressure of the exhaust chamber becomes higher than a set pressure, the fire extinguisher injects the extinguishing agent or the inert fluid into the exhaust chamber.